In an injection type internal combustion engine, represented by a diesel engine, it is necessary to operate a fuel injection pump in a manner such that it may maintain certain relationship between fuel injection quantity and rotating speed of the engine.
A governor is employed for this purpose, and a mechanical governor is utilized in many cases. Function of the governor is to actuate a control rack or a control rod by driving force of a flyweight produced in accordance with engine rotating speed, thereby rotating a plunger of the fuel injection pump to change an effective stroke thereof.
When the fuel injection pump is a relatively large one, a cam shaft actuating the fuel pump plunger is arranged to penetrate a pump housing in the longitudinal direction thereof. Thus, in this case, the governor assembly may be mounted onto a side face of the fuel injection pump housing as a part thereof, so that it is easy to allow the governor to have control function for entire the speed range since there is no limitation in terms of space therefor.
In case of a compact car, however, the engine is small, and therefore the fuel injection pump employed therefor is small, so that severe limitation is imposed on the installation space. In this case, since the cam shaft can not be provided to penetrate the pump housing, it is typical to let the fuel injection pump, as an individual element, engage with the cam shaft through an opening formed at an upper portion of the casing which rotatably supports the cam shaft, as disclosed in Japanese Patent Application Laid Open Publication No. 156925/1979.
In this case therefore, the governor itself has to be small. On the other hand, in order to freely adjust the amount of fuel injection quantity for adjustable speed and entire load conditions, enlarging of the mechanism is unavoidable.
Thereupon, the governor of this type has to have simple structure i. e., the fuel injection quantity is controlled by the balance between the governor lever and the governor spring, and governors which are not capable for speed adjustment for entire speed range from low speed to the maximum speed and for arbitrary adjustment of fuel injection for entire load conditions.